The present invention relates to determining density and uniformity of web configured material, and more particularly, to a method and device for non-invasively optically determining bulk density and uniformity of web configured material during in-line processing, based on measuring and analyzing light scattered by entire volume segments of the web configured material.
Manufacturing of a wide variety of consumer products, in a wide variety of industries, involves in-line processing of web configured materials. This includes in-line processing of web configured materials at an early, intermediate, advanced, or final stage in the overall manufacturing sequence leading to a finished product. In particular, raw materials, or, early, intermediate, advance, or final stage materials may be of a web configuration, whereby downstream manufacturing requires in-line processing of such web configured materials, eventually leading to production of the finished product.
Herein, the term ‘web configured material’, also referred to as ‘web material’, refers to any material, natural or synthetic, organic and/or inorganic, pure or mixed, whose external macro, bulk, or processing configuration or structure, in contrast to internal micro or local configuration or structure, is at least partly a web or is web-like, featuring or characterized by a uniform or non-uniform latticed, woven, interwoven, or interlaced configuration or structure. Commonly known web configured materials are natural raw materials such as wool, cotton, and flax used for manufacturing a countless number of finished products in a wide variety of industries, and, early, intermediate, advanced, or final stage materials such as natural or synthetic (for example, nylon) yarn used for manufacturing cloth, textile fabrics, feminine hygiene products, medical gauze, paper, plastic, and related products, where any of these products may also be early, intermediate, advance, or final stage materials used in an overall manufacturing sequence.
In such manufacturing sequences, web configured material exiting one process is transported by an in-line conveyor for entering another process. In going from one process to another process in a given manufacturing sequence, bulk density, and consequently, uniformity, throughout the entire volume of the web configured material may change, according to the particular operating or processing parameters of the processes involved. At this stage of the manufacturing sequence, bulk density and uniformity are often important properties of the web configured material which need to be determined, monitored, and controlled prior to the web configured material entering further downstream processes or storage. In particular, if the bulk density and/or uniformity of a given web configured material are outside of established quality control values, use of such web configured material is expected to lead to downstream intermediate, advanced, or final stage materials, or stored web configured material, similarly failing their established quality control values, potentially causing undesirable rejection of material, manufacturing down time and added cost to the finished product.
Microwave techniques, known from the prior art, are available for non-invasively determining bulk density and/or uniformity of web configured materials, such as wool and cotton, during in-line processing. In these teachings, typically, a radiation source beam is transmitted through a portion of material and is received by a receiving antenna, which then produces a signal characteristic of the material. Microwave signal parameters such as attenuation and phase shift are used to determine bulk density and/or uniformity of the material. Such techniques are applicable to relatively high bulk density loose or packaged materials, for example, having bulk densities of on the order of several kilograms per square meter, with corresponding measuring sensitivities significantly less than desirable for many current manufacturing sequences involving in-line processing of web configured materials. In particular, cost and quality of many current manufacturing sequences involving in-line processing of web configured materials could be significantly improved if there was to exist the capability of determining and monitoring bulk density in the range of from about one kilogram to essentially zero kilogram, with corresponding measuring sensitivity of the order of one gram per square meter.
There are also teachings of applying infrared spectroscopy for non-invasively determining bulk density and/or uniformity of web configured materials during in-line processing. Typically, exposed surface area of web configured material passing between manufacturing processes is subjected to an infrared beam, whose output is compared to the output of a reference or calibration beam, for obtaining in-line values of infrared reflections proportional to density and/or uniformity of the material. In practice, these teachings are significantly limited by interference during the infrared measurements, caused by the presence of varying quantities of dirt on the surface of the infrared source and receiver apparatus, and dust in the surrounding air. Moreover, such techniques are additionally limited by the infrared measurements providing information relating only to the exposed surface area of the web configured material during in-line processing, and are not capable of providing bulk density or uniformity information relating to entire volume segments of the moving web configured material. Especially for low bulk density web configured material, results of bulk density and/or uniformity obtained by such prior art techniques are significantly limited.
Aside from radiation based methods and devices, currently available methods and devices for non-invasively determining bulk density, and consequently, uniformity, of web configured material during in-line processing are typically based on measuring operating parameters, such as humidity and temperature in the immediate vicinity of the material, for determining the moisture content of the web configured material. Here, for a given temperature, the moisture content of the web configured material is proportional to bulk density, and consequently, uniformity, of the web configured material during the in-line processing. These techniques are also applicable to relatively high bulk density loose or packaged materials, having bulk densities of on the order of several kilograms per square meter, and feature relatively low measuring sensitivities.
To one of ordinary skill in the art, there is thus a need for, and it would be highly advantageous to have a method and device for non-invasively determining bulk density and uniformity of web configured material during in-line processing, featuring the capability of determining bulk density in the range of from about one kilogram to essentially zero kilogram per square meter of web configured material, with corresponding measuring sensitivity of on the order of one gram per square meter of web configured material.
Accordingly, there is thus a need for, and it would be highly advantageous to have a method and device for non-invasively optically determining bulk density and uniformity of web configured material during in-line processing, based on measuring and analyzing light scattered by entire volume segments of the web configured material during the in-line processing. Such a method and device providing accurate and precise determination of bulk density and uniformity of web configured material during in-line processing would enable achieving significantly higher levels of process optimization and control, quality control and quality assurance, and resource savings, associated with individual manufacturing processes, leading to achieving the same improvements in a large number of overall manufacturing sequences currently used for producing consumer products involving in-line processing of web configured materials.